Q2406 Datasheet, PDF (13/81 Pages) List of Unclassifed Manufacturers – SELF CONTAINED E GSM/GPRS 900/1800 OR 850/1900 BI BAND MODULE

WM_PRJ_Q2400_PTS_002 - 002
24th January 2003
2.2 Power supply
2.2.1 Power supply description
The power supply is one of the key issue in the design of a GSM terminal. Due
to the bursted emission in GSM / GPRS, the power supply must be able to
deliver high current peaks in a short time. During these peaks the ripple (U_ripp)
and the drop (U_drop) on the supply voltage must not exceed a certain limit (see
table “Power Supply Voltage” bellow).
• In communication mode, a GSM/GPRS classe 2 terminal emits 577µs
radio bursts every 4.615ms.
Udrop
Uripp
Udrop
Uripp
t = 577 µs
T = 4,615 ms
In communication mode, a GPRS class 10 terminal emits 1154µs radio bursts
every 4.615ms.
Two different inputs are provided for the power supply. The first one, VBATT is
used to supply the RF part and VDD, the second one is used to supply the
baseband part.
Notes :
• It is possible to connect VBATT to VDD.
• In case of separate power supplies, they have to be in the same state i.e
both active or inactive at the same time.
VBATT : supplies directly the RF components with 3,6 V. It is essential to keep
a minimum voltage ripple at this connection in order to avoid any phase error.
The RF Power Amplifier current (2.0 A peak in GSM /GPRS mode) flows with a
ratio of 1/8 of the time (around 577µs every 4.615ms for GSM /GPRS cl 2) and
2/8 of the time (around 1154µs every 4.615ms for GSM /GPRS cl 10). The
rising time is around 10µs.
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